ECCMID17: New test could detect colistin resistance in bacteria

Recently evidence suggests that some bacteria have become resistant to the last-resort antibiotic colistin.

In this presentation at the 27th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) (22-25 April. Vienna, Austria), researchers report that they were able to test bacteria and rapidly discover whether they were resistant to colistin. They were also able to assess how easily they might be able to pass this resistance onto other bacteria.

The findings are important as knowing which patients have the most dangerous infections could allow quarantine measures to prevent spread.

The study was part of a collaboration between Laurent Sortet (South Paris University, France) and Gerald Larrouy-Maumus and Alain Filloux (both Imperial College London, UK). The team studied Escherichia coli and Klebsiella pnuemoniae which are both members Enerobacteriacae family. causative agents of gastroenteritis, urinary tract infections, lung diseases and sepsis.

Some strains have developed resistance to nearly all available antibiotics, meaning colistin is often the only treatment. Unfortunately, some strains are now also developing resistance to this.

Previous research has shown two types of colistin resistant in bacteria, first is chromosome-encoded resistance, which can only be passed on by division, the other type is plasmid-encoded resistance, which can be passed horzintally via gene transfer.

Dortet comented: “This plasmid-encoded resistane is particularly worrying because it has the potential to spread quickly and easily and if that happens, last resort drugs like colistin could also become obsolete. If, on the other hand, we are able to rapidly identify bacteria that have these type of resistant we can take measures to stop its spread, this might include isolating the patient in a seperate room where they are treated by dedicated medical staff.”

The team tested 134 different colonies of bacteria with mass spectrometry, a technique found at most hospitals, discovering it was possible to not only identify bacteria that are colistin resistant but also to identify which bacteria possess plasmid-encoded resistance. The test can be conducted in approximately 15 minutes and costs less than US$1 per sample.

Larroy-Maumus explained: “The most exciting thing about this technique is that it relies on technology that is already available in most hospitals. This means it could be rolled out quickly and cheaply and potentially have a rapid impact on tackling drug resistance.”

The team suggest that their technique could also be utilized to analyze veterinary samples or test new drugs hoping to restore colistin susceptibility. The researchers are now working to patent the technique and develop it for widespread use in hospital laboratories.